1. Field of the Invention
The invention relates to a process for the preparation of a detergent powder composition containing a bleach activator for peroxy compounds. More particularly the invention relates to a method of incorporating an organic activator for peroxy compounds in detergent powder formulations. The invention also relates to a process for washing and/or bleaching textiles with the aid of a washing and/or bleaching liquid prepared from the detergent compositions according to the invention.
In the present context, the term "textiles" includes natural and synthetic fibres, as well as fabrics or products manufactured therefrom and therewith.
2. Description of the Prior Art
It is well-known in washing and/or bleaching textiles to make use of compositions containing inter alia peroxy compounds, particularly inorganic peroxy compounds, having a bleaching effect on the textiles to be treated. Examples of inorganic peroxy compounds are inorganic persalts, such as the alkali metal perborates, percarbonates, perphosphates, persilicates and persulphates, hydrogen peroxide and sodium peroxide. However, washing and/or bleaching compositions containing such inorganic peroxy compounds generally have the disadvantage that their bleaching effect is relatively low at temperatures below 80.degree. C, which gives rise to difficulties when these compositions are used in machines for household purposes in which the temperature of the wash-water is not higher than 70.degree. C. The addition of bleach activators, particularly organic activators for the peroxy compound, to such compositions is known, owing to which the active oxygen of the peroxy compound becomes effective also at temperatures below 80.degree. C.
The exact mode of action of the organic activators is not known, but it is believed that organic peracids are formed by reaction of the organic activators with the inorganic peroxy compound, which peracids then liberate active-oxygen by decomposition.
Many organic activators are known in the art and have been extensively described in the literature. These are generally compounds which contain N-acyl or O-acyl residues in the molecule and which exert their activating action on the peroxy compounds on contact with these in the washing liquor.
A representative but by no means comprehensive list of known organic activators is given below:
1. Acyl organoamides of the formula RCONR.sub.1 R.sub.2, where RCO is a carboxylic acyl radical, R.sub.1 is an acyl radical and R.sub.2 is an organic radical, as disclosed in U.S. Pat. No. 3,117,148. PA0 2. Acylated sulphonamides, such as N-methyl-N-benzoylmenthane sulphonamide and N-phenyl-N-acetyl methane sulphonamide, as disclosed in U.S. Pat. No. 3,183,266. PA0 3. Carboxylic esters of the type as disclosed in British patent specification No. 836,988. Examples of activators of this type include phenyl acetate, sodium acetoxy benzene sulphonate, trichloroethylacetate, sorbitol hexaacetate, fructose-pentaacetate, p-nitrobenzaldehyde diacetate, isopropenyl acetate, acetyl aceto hydroxamic acid, and acetyl salicylic acid. Other examples are esters of a phenol or substituted phenol with an alpha-chlorinated lower aliphatic carboxylic acid, such as chloroacetylphenol and chloroacetylsalicylic acid, as disclosed in U.S. Pat. No. 3,130,165. PA0 4. Acyl-cyanurates, such as triacetyl- or tribenzoylcyanurates, as disclosed in U.S. Pat. No. 3,332,882. PA0 5. Carbonic acid or pyrocarbonic acid esters of the formula R.sub.1 OCOOR.sub.2 or R.sub.3 OCO-OCO-OR.sub.2, as disclosed in British patent specification No. 970,950, for example p-carboxy-phenylethyl-carbonic acid ester, p-carboxyphenyl-ethyl pyrocarbonic acid ester, and sodium sulpho phenylethyl carbonic acid ester. PA0 6. Optionally substituted anhydrides of benzoic or phthalic acid, for example benzoic anhydride, m-chlorobenzoic anhydride and phthalic anhydride. PA0 35 gms sodium dodecyl benzene sulphonate PA0 9 gms anhydrous soap PA0 9 gms tallow alcohol/18 ethylene oxide PA0 197 gms sodium triphosphate PA0 275 gms water PA0 25 gms organic activator. PA0 1. 2-40%, preferably 5-25% by weight of surface-active agents or mixtures of surface-active agents, comprising: PA0 2. 0-5%, preferably 0.5-3% by weight of a foam stabilizer. PA0 3. 0-5%, preferably 0.5-3% by weight of a foam inhibitor. PA0 4. 10-80%, preferably 25-70% by weight of builder material and alkaline agents. PA0 5. 2-40%, preferably 4-35% by weight of a peroxy compound, e.g. sodium perborate, sodium percarbonate, etc. PA0 6. 0-30%, preferably 2-20% by weight of fillers. PA0 7. 0.5-20%, preferably 1-15% by weight of an organic activator. PA0 8. 0-20%, preferably 2-15% by weight of other adjuncts and ingredients, such as for example optical brighteners, soil-suspending agents, dyestuffs, perfume, enzymes, and moisture. PA0 1. TAED was stable in slurries over the pH range of 9.2-9.4 (measured on 1% solution) at the working temperature of 80.degree. C; no decomposition was detected over an 1 hour ageing period. PA0 2. Concentrations of organic volatile in the tower exhaust gases were low, and compare favourably with levels found in processing conventional powders, which is indicative to the very low loss of organic activator in the blown powder. PA0 3. Powders blown to nominal moisture contents (about 12-14%) contained the required level of TAED, confirming the low loss of TAED as monitored during processing. The powder exhibited satisfactory performance characteristics and showed no apparent loss of TAED after 2 weeks' storage under ambient conditions. PA0 1. slurry making (50:50 TAED/water) PA0 2. colloid milling PA0 3. drum drying PA0 4. mixing PA0 5. extruding PA0 6. spheronizing PA0 7. sieving.
Examples of compounds falling under this group are:
A. N,N-diacetylaniline and N-acetylphthalimide. PA1 B. N-acylhydantoins, such as N,N'-diacetyl-5,5-dimethylhydantoin. PA1 C. Polyacylated alkylene diamines, such as N,N,N.sup.1 N.sup.1 -tetraacetyl-methylene diamine and N,N,N.sup.1,N.sup.1 -tetraacetyl-ethylene-diamine, as disclosed in British patent specification No. 907,356. PA1 d. Acylated glycolurils, such as tetraacetylglycoluril, as disclosed in British patent specification No. 1,246,338. PA1 0-100%, preferably 20-65% by weight of synthetic anionic surface-active compounds of the sulphonate and/or sulphate type. PA1 0-100%, preferably 5-50% by weight of nonionic surfce-active compounds. PA1 0-100%, preferably 5-50% by weight of an alkali-metal soap of C.sub.8 -C.sub.22 fatty acids. PA1 Slurry rheology was not affected by TAED and conventional slurry moisture contents (about 45-50%) can be used.
The manufacture of detergent compositions, particularly fabric washing compositions, in the form of a coarse powder by the spray-drying technique is well-known, in which all the non-heat-sensitive and non-hydrolysable ingredients are slurried together with water to produce a fairly viscous paste which is pumped directly to a spray-jet of a tower where the product is both cooled and dried, in such a way that the resulting powder has a fairly large particle size with satisfactory solubility characteristics. The slurry generally comprises two basic ingredients, i.e., surface-active agents and builder materials. In addition thereto and if desired, other useful adjuncts and ingredients are generally present, such as fillers, e.g. sodium sulphate; lather stabilizers, e.g. coconut diethanolamide; lather depressants; soil-suspending agents, e.g. sodium carboxymethylcellulose; alkaline agents, e.g. alkaline silicates; optical brighteners; metal sequestering agents, e.g. ethylene diamine tetraacetate (EDTA), dyestuffs, etc.
Where the formulation requires the presence of a peroxy compound bleach, such as sodium perborate, it is not possible to include this ingredient in the detergent slurry which is fed to the spray-drying tower, since it would readily decompose with loss of active oxygen. In view of this, peroxy compounds are usually added to the final detergent powder after drying and cooling have taken place, and are mixed at the base of the spray-drying tower, i.e., secondary dosing. In preparing a detergent bleach composition which comprises also an organic activator for the peroxy compound, the organic activator being a hydrolysable material, is hitherto also added to the final detergent powder after drying and cooling have taken place, i.e., by the so-called secondary dosing. Not only does secondary dosing form an additional processing step requiring quite elaborate and accurate dosing systems, in view of difference in physical characteristics of the powders, it brings in also the risk of segregation in the pack during transport and storage.
Often, the organic activator, being a hydrolysable material, is further protected from moisture and the alkaline components of the detergent composition during storage, either by coating with an inert material or by forming particles in which the activator is imbedded in a carrier material, or by a combination of both. Various techniques and various coating and/or carrier materials have been suggested for use in this step which was hitherto thought desirable for preserving the detergent bleach compositions from deterioration. Such methods of protection are disclosed in e.g. British patent specifications Nos. 907,358, 1,204,123, 1,246,338 and 1,360,427 and Netherlands patent application 7205871.